INFLUENCE OF SUPERPLASTICIZER TYPE AND DOSAGE ON RETENTION OF CONSISTENCY OF RUBBERIZED CONCRETE

Concrete with recycled rubber as a partial replacement of fine natural aggregate, intended for use in load-bearing structural elements, requires specific fresh concrete properties such as a particular slump and flow classes. These specific requirements can be caused by increased water or superplasticizer content. Therefore, concrete mixtures with different percentages of two types of superplasticizers A1 and A2, i.e. 0.2, 0.4 and 0.6% by cement mass, were prepared. Furthermore, the effect of retention of consistency after 15, 30, 45, 60, and 90 minutes, was also studied. Slump and flow table tests were performed at 15-minute intervals to determine the fresh performance of each concrete mixture and retention of consistency. Test results indicate that mixtures with superplasticizer A2 show a more uniform workability range during the measurement period and at the end of the measurement, remain within the same consistency classes, as in the initial measurement.